PERSISTENCE 153 



The surf is much more persistent, and much more regular in its 

 characteristics, along the western coast of the United States than 

 along the eastern, because the prevailing winds are more often on- 

 shore there, and so tend to build up the waves (seas or swells) that 

 come in from the seaward, or at least do not tend to beat them down. 

 The surf that is raised daily through the summer, near Monterey, 

 Calif., by the brisk sea breeze that springs up with astonishing regu- 

 larity each morning at that season, to die down again at sunset or 

 soon after, affords a good illustration of this regularity. 



Surf caused by waves that are generated nearby dies so soon after 

 the wind falls, or when the latter shifts in direction (because of the 

 decrease that takes place then in the sizes of the waves offshore), that 

 the breakers due to storm seas may decrease to manageable propor- 

 tions within a few hours. But a dying wind or even a calm, near 

 the beach, may not decrease the surf at all if the breakers are caused 

 by swells coming from a distance. This phenomenon is of much prac- 

 tical importance, for anyone not instructed in the matter might nat- 

 urally expect to find landing easy in calm weather, whereas the surf 

 from a swell may actually persist for a considerable period of time 

 even in a flat calm, as described above (p. 99) . We ourselves observed 

 a very regular and persistent swell on one occasion, on the west coast 

 of Ceylon, throughout the 36 hours of our stay, although there was 

 hardly a breath of wind stirring. A light cross wind may also inter- 

 fere very little with surf from an old swell, so long as the waves pro- 

 duced by the wind are not large enough to interfere seriously with 

 the wave pattern of the swell, and a heavy surf may even persist 

 against a strong offshore wind (fig. 44) until the latter has had time 

 to kill the waves offshore, because the time occupied by each breaker 

 in its development over the shoaling bottom is not long enough for 

 the wind to combat it effectively before it reaches the breaker line. 



